Polypropylene is a thermoplastic widely used to manufacture plastic containers, bottles, structural components, films for packaging and a host of other materials. More than 10 billion pounds of polypropylene are produced worldwide each year. All commercial polypropylene today is composed of isotactic polypropylene, (the molecular chain structure has the methyl group side branches all placed on the same side with respect to the polymer chain backbone), or atactic polypropylene (the methyl group side branches are placed at random with respect to the polymer chain backbone).
Recently it has become feasible to produce a new type of polypropylene called syndiotactic polypropylene in which the methyl group side branches are placed on alternating sides of the polymer chain backbone. Syndiotactic polypropylene has been found to have properties quite different from that of previous isotactic and atactic polypropylenes. Since the chain microstructure and crystallization behavior of these semi-crystalline syndiotactic polypropylene polymers are significantly different than that of isotactic polypropylene polymers, syndiotactic polypropylene cannot automatically be used as a direct substitute in any current process where isotactic polypropylene is used.
Thus, there have appeared in the art methods for processing and making molded articles of syndiotactic polypropylene. For example, European Patent Application 428,972 discloses a method for making molded articles of syndiotactic polypropylene comprising heating, melting, then hot molding a homopolymer of syndiotactic polypropylene followed by quenching and optionally followed by heat treatment at a temperature less than the melting point of the syndiotactic polypropylene. (Quenching is a method used in the art to control crystallization in polyolefin processing). 972's method does not provide, however, a method for molding, shaping or forming the polymer at temperatures below 80.degree. C. Thus, it is desirable that methods for modeling syndiotactic polypropylene at temperatures below 80.degree. C. be provided. It would be further desirable if there were provided a method to process syndiotactic polypropylene such that syndiotactic polypropylene could be utilized as freely as isotactic polypropylene.